LK's HC90 CMM Benefits Equipped with automatic probe changer Accommodates large measurements Operates at up to 39m/min Integrates with CAD systems www.lk-cmm.com

CMMs Help Jaguar Improve Manufacturing Accuracy

Jaguar Cars Ltd. improved sheet metal matching and profiles by installing a new CMM from LK Metrology Systems Inc. The HC90 CMM, coupled with LK's CAMIO software, brought the luxury car company impressive manufacturing accuracy, a need spawned by increased consumer quality awareness.

New car buyers are able to detect surprisingly small variations in gap widths and profiles. In response to the demand for higher levels of precision, Jaguar has decreed that certain sedan models will maintain more narrow tolerances with respect to sheet metal matching surfaces and profiles. Typically, the new standard will require measurements accurate to within half a millimeter.

To meet their lofty new goal, the quality department at Jaguar's Castle Bromwich factory must be able to measure to 0.002", ten times better than was possible with their previous equipment. Moreover, new gage reliability and reproducibility requirements demand a working range of just 15 percent of that figure. LK's HC90, therefore, must be accurate within 7.5 microns while recording measurements over its ample size. The CMM, with its 20.6' x 5.2' x 8.2' volume, can accommodate an entire car body.

The HC90 features twin rails, twin ceramic arms and columns, and computer control. Previously, Jaguar utilized traditional dedicated ring fixtures, which occupied more factory space because of the need for measurement devices specific to only a few types of measurement. In addition, the traditional measurement fixtures were time consuming to construct and, therefore, not cost effective.

Phil Hall, Jaguar's plant quality superintendent, is responsible for ensuring the efficiency of and quality of the production line. "It is much more cost effective," he says, "to modify an inspection program [with a CMM] than to make a dedicated check fixture."

The HC90 improves efficiency in large part because of its ability to accommodate a variety of needs. At Jaguar, the same HC90 holding fixture is designed to accept a number of different body parts, including the front side rail assembly, complete front end assembly, rear end under frame, complete under frame, main fall assembly and front fenders.

Originally, Jaguar installed the HC90 at Castle Bromwich in April 1997. Located in a temperature-controlled room adjacent to the production line, it was used on the prototype stage of the S-Type Jaguar sedans. Within a week of its installation, the LK CMM was checking the first prototype body. Additionally, the machine was employed during this phase for mass data collection to investigate prototype build issues. For instance, the HC90 found that one of the rear doors was originally too tight to the body, and the press tool was modified accordingly.

As full production of the S-Types is now underway, the HC90 is a busy machine. One complete car body is checked per day, representing a sampling rate of one in 100. Also, a body without installed doors is checked three times a week. Excluding the 60 primary locations on each vehicle that are checked at a measuring station on the line, Jaguar uses its new CMM for all other testing on a sample basis.

Very satisfied with the HC90, Jaguar also uses other LK equipment. It recently installed an LY90, a layout CMM. One advanced feature of the new Castle Bromwich metrology facility is the new found ability to use both of the company's CMMs in cooperation with the existing CAD system.

LK adopted its CAMIO software to integrate with Jaguar's CAD system. Files in PDGS can be formatted from Jaguar's CAD system for a PC. The computer that runs the CAMIO software converts geometrical data into measuring routines while offline. By the time programs are proved and released to the CMMs they are 90-percent correct, requiring only a small amount of editing for machine control. The improvements LK made to CAMIO with Jaguar have now been incorporated into LK's standard software package.

New elements of CAMIO facilitate reporting by combining measured results in a Microsoft Excel database with CAD files. From this marriage of technologies, Jaguar can produce a quality booklet on every measured vehicle as soon as measurements are completed.

For example, introduced weighted score matrixes, which indicate the size of errors, allow engineering activities to be prioritized. It is also now possible to associate pictorial and trend charts on the same chart. This new ability allows presentations to be more quickly and easily understood. "Hundreds of thousands of measured results have to be managed and interpreted, so it is crucial to have an efficient reporting system," states Hall.